\documentclass{standalone}
\usepackage{tikz}
\usepackage{ctex,siunitx}
\setCJKmainfont{Noto Serif CJK SC}
\usepackage{tkz-euclide}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{circuitikz}
\usetikzlibrary{patterns, calc}
\usetikzlibrary {decorations.pathmorphing, decorations.pathreplacing, decorations.shapes,}
\ctikzset{bipoles/length=1cm}
\begin{document}
\small
\begin{circuitikz}[>=latex, scale=1.0,european]
  % \useasboundingbox(0.9,0)rectangle(5.1,5);
  \draw[densely dashed,thin](-0.5,0)--(6,0);
  \draw[semithick](0,0)parabola(4,-0.25);
  \draw[->,semithick](4,-0.25)--(5,-0.375);
  \draw[thin](4.5,0)--(4.5,-0.3125)node[midway,right]{$y$};
  \draw[very thick] (0,0.5)--(4,0.5)(0,-0.5)--(4,-0.5);
  \foreach \x in {0.2,0.8,...,3.9}
  {
    \node at (\x,0.4) {\tiny$+$};
    \node at (\x,-0.4) {\tiny$-$};
  }
  \foreach \x in {-0.7,-1.0,-1.3,-1.6,-1.9}
  {
    \draw (\x,0) circle (3pt);
    \node at (\x,0) {\tiny$+$};
  }
  \node at (-1.3,0)[above=1mm]{$v_0$};
  \draw[thin](0,0.6)--++(0,0.7)(4,0.6)--++(0,0.7);
  \draw[thin,<->](0,1.0)--(4,1.0)node[midway,above]{$\ell$};
  \draw(0.5,0.5)--(0.5,0.75)--(-2.1,0.75)--(-2.1,-1.5)to[battery](0.5,-1.5)--(0.5,-0.5);
  \begin{scope}[xshift=4cm,yshift=-1.5cm]
    \draw[semithick,->](0,0)--(3.2,0)node[midway,above]{$v_0$};
    \draw[semithick,->](0,0)--(3.2,-0.4)node[midway,below]{$v$};
    \draw[semithick,->](3.2,0)--(3.2,-0.4)node[midway,right]{$v_\perp$};
    \draw[thin](2.5,0)arc(0:-7.125:2.5)node[midway,right]{$\phi$};
  \end{scope}
\end{circuitikz}
\end{document}